JPH01298918A - Charger - Google Patents

Abstract

PURPOSE:To eliminate the connection of a temperature fuse to an electric circuit at the time of discharge and to effectively detect the temperature rise of a battery pack by disposing the fuse provided in a charging circuit on a face in which the pack is mounted. CONSTITUTION:A charger 3 having a charging circuit 33 including a transformer 41, a rectifier 42, a control circuit 44 for controlling a control element 43 in a body 30 comprises a recess 31 in which a battery pack 2 is inserted on one face of the body 30. A temperature fuse 5 connected in series with an anode terminal 47 is disposed in a cutout 32 formed on the inner wall of the recess 31. When the pack 2 is inserted into the recess 31 to be charged, the fuse 5 is in a state to be substantially brought into contact with the outer face of the pack 2. Accordingly, the temperature rise of the pack 2 can be effectively detected. Since the fuse is not connected to an electric circuit at the time of discharge, a large current discharge can be conducted.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a charging station consisting of a battery pack containing a secondary battery and a charger in which the battery pack is detachable and has a built-in charging circuit, and particularly relates to improvements in safety against battery temperature rise. It is something.

[Prior art 1] A secondary battery used in a rechargeable power tool or the like is usually a battery pack 2 housed in a case 20 and detachable from the power tool 1, as shown in FIG. The secondary battery is charged by connecting it to the charger 3 shown in FIG. 10. In the fast charging type, which allows charging in a short period of time such as one hour, the charger 3 has the following functions as shown in Fig. 11.
A charging circuit 33 includes a transformer 41, a rectifier 42, and a control circuit 44 that controls a control element 43 such as a transistor or a thyristor, and has an anode terminal 47, a cathode terminal 48, and a sensor terminal 49 as output terminals.
The battery pack 2 houses a plurality of secondary batteries 21 and a sensor S in a case 20, and also includes an anode terminal 27, a cathode terminal 28, and a sensor terminal 29. There is. The sensor S here is a diode or thermistor for temperature compensation of the battery voltage when the charging control method is a voltage detection method, and is a thermostat when the charging control method is a temperature control method. In either case, it is placed in the case 20 in contact with or in close proximity to the secondary battery 21. By the way, in these devices that can be charged quickly,
Since charging is performed with a large current, if the charging current control system fails and the charging current cannot be controlled, the charging current that continues to flow even after charging is completed will cause overcharging of the secondary battery, and hydrogen will In the case of pack-type batteries, the heat dissipation properties of the batteries are not good, causing the internal temperature to rise rapidly and dramatically shorten the battery life. In addition, it may cause deformation of the case. [Problems to be Solved by the Invention] In order to prevent this temperature rise, it is conceivable to provide a temperature fuse connected in series with the secondary battery within the battery pack. However, for products used in power tools, etc., the load current is a large current of several tens of amperes, and there is no thermal fuse that can pass such a large current. Since the terminals are shared between the temperature fuse and the discharge terminal, the internal resistance of the temperature fuse causes a voltage drop during discharge, which has a significant impact on the performance of the tool. is not used. The present invention has been made in view of the above points, and its purpose is to prevent overcharging and temperature rise of the secondary battery even when the control system of the charging circuit fails and uncontrolled charging occurs. An object of the present invention is to provide a charging device that can reliably prevent this by using a temperature fuse. [i! Means for Solving Problem 1] The charging device according to the present invention includes a battery pack containing a secondary battery, a charger in which the battery pack is detachable and has a built-in charging circuit. The battery charger is characterized in that a temperature fuse connected to the charging circuit is provided inside the charger, and the temperature fuse is disposed on the surface on which the battery pack is mounted. <Function> According to the present invention, the temperature fuse is connected only when charging the secondary battery, and even though the temperature fuse is located on the charger side, it is possible to reliably detect a temperature rise in the battery pack. be able to. <Example> The present invention will be explained below based on the illustrated example.
The figure and FIG. 2 show one embodiment, in which a charging circuit 33 consisting of a transformer 41, a rectifier 42, and a control circuit 44 for controlling a control element 43 made of a transistor or a cyrisk is provided inside the container body 30. The charger 3 includes a recess 31 on one side of its container body 30 into which the battery pack 2 is inserted. Inside this recess 31 are an anode terminal 47 and a cathode terminal 48 as output terminals, as well as a sensor terminal 4.
A temperature fuse 5 connected in series with an anode terminal 47 is arranged in a notch 32 formed in the inner wall of the recess 31 . When charging the battery pack 2 by inserting it into the recess 31, the temperature fuse 5 is in almost contact with the outer surface of the battery pack 2, so it is not possible to reliably detect the temperature rise of the battery pack 2. When the temperature of the battery pack 2 rises significantly, such as when the charging current control system fails, the temperature fuse 5 operates to cut off the charging current. As shown in FIGS. 3 and 4, a notch 23 is provided in the case 20 of the battery pack 2, and the temperature fuse 5 is disposed to protrude into the recess 31.
If the temperature fuse 5 is located in the notch 23 when the battery is inserted into the
can be detected more reliably. As shown in FIG. 5 and FIG. It is also possible to provide a four part 25 into which the part 35 fits. In this case, as shown in FIG. 7(a)(+))(e), the four part 2
Reference numeral 5 is assumed to be located between a plurality of secondary batteries 21 inside the battery pack 2. Furthermore, as shown in FIG. 8, the temperature fuse 5 has one end fixed to a contact spring 50 made of a good thermal conductor, and when the battery pack 2 is inserted into the recess 31, the other end of the contact spring 50 passes through the notch 23. The thermal fuse 5 itself may be brought into contact with the secondary battery 21 or may be brought into contact with the secondary battery by being biased by a spring.

【Effect of the invention】

As described above, in the present invention, since the temperature fuse is located on the charger side, the temperature fuse does not enter the electrical circuit during discharging, and large current discharge can be performed without any problem.Moreover, the temperature fuse is located on the charger side. However, since the temperature fuse is placed on the surface where the battery pack is installed, it can reliably detect the rise in temperature of the battery pack, ensuring safety in the event of a failure in the charging current control system. can be carried out reliably.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of one embodiment of the present invention, Fig. 2 is a circuit diagram of the above, Fig. 3 is a sectional view of another embodiment, Fig. 4 is a perspective view of the battery pack of the above, Figs. t1116 is an exploded sectional view and a sectional view of another embodiment, FIGS. 7(aHb) and 7(c) are horizontal sectional views showing an example of the arrangement position of the opening in the same battery pack, and FIG. 8 is another example. 9 is an explanatory diagram of a battery pack for a power tool, FIG. 10 is a perspective view of the same charging device as above, and FIG. 11 is a circuit diagram of a conventional example, where 2 is a battery pack, 3 is a circuit diagram of a conventional example, and FIG. 5 is a charger, 5 is a temperature fuse, 21 is a secondary battery, 31 is a recess, and 33 is a charging circuit. Agent Patent Attorney Stone 1) Ai 72 Battery pack 3 Photoelectric device 5 Temperature fuse 31 Recess Figure 4 33 Charging circuit Figure 2 Figure 3 Figure 6 Figure 8 Figure 9 Figure 10

Claims (1)

[Claims] (1) In a battery pack containing a secondary battery and a charger in which the battery pack is detachable and has a built-in charging circuit, the battery pack is connected to the charging circuit within the charger. A charging device characterized in that a thermal fuse is provided and the thermal fuse is arranged on a surface on which a battery pack is mounted.